kmapset_lookup() walks map->links with hlist_for_each_entry_rcu() and its
own comment states the contract: the caller holds kmapset_lock (the set
mutex) or rcu_read_lock. Its readers take rcu_read_lock and its writers
(kmapset_set_value, kmapset_del_value) hold kmapset_lock, so callers that
honour the contract are serialised correctly. The macro carried no lockdep
condition though, so with CONFIG_PROVE_RCU_LIST the writer path trips:
lib/kmapset.c:236 RCU-list traversed in non-reader section!!
kmapset_lookup
kmapset_del_value
kernfs_perms_set
Pass lockdep_is_held(&map->set->mutex) so the checker accepts both the
rcu_read_lock readers and the kmapset_lock writers. No functional change.
Fixes: 8e1c907a00e8 ("kmapset: set of key-value mappings with build-in")
Signed-off-by: Mirian Shilakadze <[email protected]>
---
lib/kmapset.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/lib/kmapset.c b/lib/kmapset.c
index c7a1e57ad3a5..a479134b9793 100644
--- a/lib/kmapset.c
+++ b/lib/kmapset.c
@@ -233,7 +233,8 @@ kmapset_lookup(struct kmapset_map *map, struct kmapset_key
*key)
{
struct kmapset_link *link;
- hlist_for_each_entry_rcu(link, &map->links, map_link) {
+ hlist_for_each_entry_rcu(link, &map->links, map_link,
+ lockdep_is_held(&map->set->mutex)) {
if (link->key == key)
return link;
if (link->key > key)
--
2.43.0
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